Electrically conductive magnetic shield laminate structure for contact recording sensor

ABSTRACT

In one general embodiment, an apparatus includes a magnetic sensor structure, a magnetic shield having at least one laminate pair comprising a magnetic layer and an electrically conductive nonmagnetic layer, and a nonmagnetic spacer layer between the sensor structure and the magnetic shield. In another general embodiment, an apparatus includes a magnetic tunnel junction sensor structure, and a magnetic shield having at least two laminate pairs, each pair comprising a magnetic layer and an electrically conductive nonmagnetic layer. A deposition thickness of the nonmagnetic layer in each laminate pair is about 10% or less of a total deposition thickness of the laminate pair.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to the prevention of shortingand/or erosion in tape heads.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

BRIEF SUMMARY

An apparatus according to one embodiment includes a magnetic sensorstructure, a magnetic shield having at least one laminate paircomprising a magnetic layer and an electrically conductive nonmagneticlayer, and a nonmagnetic spacer layer between the sensor structure andthe magnetic shield.

An apparatus according to another embodiment includes a magnetic tunneljunction sensor structure, and a magnetic shield having at least twolaminate pairs, each pair comprising a magnetic layer and anelectrically conductive nonmagnetic layer. A deposition thickness of thenonmagnetic layer in each laminate pair is about 10% or less of a totaldeposition thickness of the laminate pair.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8 is a partial side view of a media facing side of an apparatusaccording to one embodiment.

FIG. 9A is a partial side view of a media facing side of an apparatusaccording to one embodiment.

FIG. 9B is a partial side view of a media facing side of an apparatusaccording to one embodiment.

FIG. 10 is a partial side view of a media facing side of an apparatusaccording to one embodiment.

FIG. 11 is a partial side view of a media facing side of an apparatusaccording to one embodiment.

FIG. 12 is a partial side view of a media facing side of an apparatusaccording to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, an apparatus includes a magnetic sensorstructure, a magnetic shield having at least one laminate paircomprising a magnetic layer and an electrically conductive nonmagneticlayer, and a nonmagnetic spacer layer between the sensor structure andthe magnetic shield.

In another general embodiment, an apparatus includes a magnetic tunneljunction sensor structure, and a magnetic shield having at least twolaminate pairs, each pair comprising a magnetic layer and anelectrically conductive nonmagnetic layer. A deposition thickness of thenonmagnetic layer in each laminate pair is about 10% or less of a totaldeposition thickness of the laminate pair.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may include at least oneservo channel and at least one data channel, each of which include dataflow processing logic configured to process and/or store information tobe written to and/or read from the tape 122. The controller 128 mayoperate under logic known in the art, as well as any logic disclosedherein, and thus may be considered as a processor for any of thedescriptions of tape drives included herein, in various embodiments. Thecontroller 128 may be coupled to a memory 136 of any known type, whichmay store instructions executable by the controller 128. Moreover, thecontroller 128 may be configured and/or programmable to perform orcontrol some or all of the methodology presented herein. Thus, thecontroller 128 may be considered to be configured to perform variousoperations by way of logic programmed into one or more chips, modules,and/or blocks; software, firmware, and/or other instructions beingavailable to one or more processors; etc., and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (internal or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle a with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B may be made of the sameor similar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complementarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeably. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (—),cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor 234 forsensing a data track on a magnetic medium, a second shield 238 typicallyof a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known aspermalloy), first and second writer pole tips 228, 230, and a coil (notshown). The sensor may be of any known type, including those based onMR, Giant magnetoresistance (GMR), anisotropic magnetoresistance (AMR),tunneling magnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads. Moreover, unless otherwisespecified, processes and materials of types known in the art may beadapted for use in various embodiments in conformance with the teachingsherein, as would become apparent to one skilled in the art upon readingthe present disclosure.

As mentioned above, contact recording systems such as tape drive systemsmove media such as magnetic tapes over the surface of the read and/orwrite heads at high speeds. Tape drive systems usually implement aminimized spacing between the head and the tape. However, as tape ispassed over magnetic heads in conventional products, defects such asasperities or localized abrasive bumps on the surface of the tape itselfmay create electrical shorts by smearing and/or scratching conductivematerial across the tape head, such as across a read sensor. As aresult, conventional products may experience shorting of read sensorsand consequential inoperability thereof after ordinary use, particularlywith new, unworn media.

In sharp contrast, tape drive systems described herein may include oneor more magnetic layer and electrically conductive nonmagnetic layerpairings to protect the tape head, e.g., from erosion, smearing and/orscratches, which would otherwise cause electrical shorting events, etc.

FIG. 8 depicts an apparatus 800 in accordance with one embodiment. As anoption, the present apparatus 800 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchapparatus 800 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 800 presented herein may be used in any desired environment.

Apparatus 800 includes a magnetic sensor structure 812. In preferredembodiments the magnetic sensor structure 812 may be a currentperpendicular to plane (CPP) sensor structure. According to an exemplaryapproach, the magnetic sensor structure 812 may be a magnetic tunneljunction sensor structure. Accordingly, in some approaches the magneticsensor structure 812 may include a tunnel barrier layer of a type knownin the art. It follows that, depending on the desired embodiment,additional layers may be present in the magnetic sensor structure 812 aswould be appreciated by one skilled in the art upon reading the presentdescription. Moreover, unless otherwise specified, the various layers inthe magnetic sensor structure 812 and other embodiments may be formedusing conventional processes.

Apparatus 800 further includes a magnetic shield 820 below the magneticsensor structure 812 and a second magnetic shield 822 above the magneticsensor structure 812. Additionally, a nonmagnetic spacer layer 810 maybe included between the sensor structure 812 and the magnetic shield820. The nonmagnetic spacer layer 810 may assist in setting the shieldto shield spacing 818, which may generally correspond to the linear datadensity of a data track readable by the apparatus 800.

The nonmagnetic spacer layer 810 may include Iridium (Ir), Tantalum(Ta), Titanium (Ti), Ruthenium (Ru), NiCr, etc., and/or othernonmagnetic, electrically conductive spacer layer materials of a typeknown in the art. Furthermore, distal portions of the nonmagnetic spacerlayer 810 may include plated permalloy, e.g., in order to facilitatewafer processing. An illustrative thickness of the nonmagnetic spacerlayer 810 may be about 1-3 nanometers, but could be higher or lowerdepending on the embodiment. In some embodiments, each nonmagneticspacer layer 810 is thicker than the electrically conductive nonmagneticlayers 808 in the laminate pairs.

The magnetic shield 820 in various embodiments may optionally have anon-laminated magnetic portion 802 (which can be formed using, e.g.,plating, sputtering, etc.; and preferably by plating for films thickerthan 0.3 microns) and a laminated portion 814. The laminated portion 814may include one, but preferably includes at least two laminate pairs816, where each laminate pair 816 includes a magnetic layer 806 pairedwith an electrically conductive nonmagnetic layer 808. However,according to various embodiments, the magnetic shield 820 may includeone, at least three, at least four, at least six, ten or more, multiple,etc. laminate pairs 816, but could include more or fewer, e.g.,depending on fabrication limitations, material characteristics, etc.

Because the laminate pairs 816 are electrically conductive, the shieldmay be used as a lead in a CPP sensor structure, as would be appreciatedby one skilled in the art upon reading the present description.

One or more of the magnetic layers 806 may include permalloy, CZT,magnetically similar alloys, etc., and/or other magnetic materials of atype known in the art such as Fe(N). Moreover, one or more of theelectrically conductive nonmagnetic layers 808 may include Iridium (Ir),Tantalum (Ta), Titanium (Ti), Ruthenium (Ru), NiCr, etc., and/or otherrelatively dense, hard and/or non-ductile electrically conductivenonmagnetic materials of a type known in the art. It should be notedthat while the electrically conductive nonmagnetic materials used toform some of the electrically conductive nonmagnetic layers 808 of thetwo or more laminate pairs 816 may share the same material type (e.g.,some of the electrically conductive nonmagnetic layers 808 may includethe same materials), the electrically conductive nonmagnetic materialsused to form other electrically conductive nonmagnetic layers 808 of thetwo or more laminate pairs 816 may vary from one another, depending onthe desired embodiment. Similarly, the magnetic materials used to formsome of the magnetic layers 806 among the two or more laminate pairs 816may be the same, while the magnetic materials used to form othermagnetic layers 806 among the two or more laminate pairs 816 may differbetween the two or more laminate pairs 816.

Implementing a laminated portion 814 having several laminate pairs 816allows for improved overall shield characteristics. For example, theelectrically conductive nonmagnetic layers 808 may implement robustmaterials thereby providing the magnetic shield 820 improved resistanceto wear, while the magnetic layers 806 may preserve the magneticfunctionality of the magnetic shield 820. Furthermore, the electricallyconductive nonmagnetic layers 808 preserve the functional conductivityof the corresponding tape head, thereby enabling the implementation of amagnetic sensor structure 812 that is a magnetic tunnel junction sensorstructure having a tunnel barrier layer, as would be appreciated by oneskilled in the art upon reading the present description.

It follows that laminate pairs 816 may prevent substantial wear of thetape head in areas where media, e.g., tape, passes over the head withouthindering performance. This improved resistance to wear provided by thesmear-resistant and/or abrasion-resistant conductive magnetic shieldconfigurations described herein, e.g., such as the configuration ofapparatus 800, is particularly desirable in view of the continuedefforts to reduce track widths and more particularly the space betweenmagnetic shields and the separation between head and tape.

Moreover, the inventors discovered that the magnetic shieldingproperties of the magnetic shields 820, 822 may be enhanced byimplementing laminate pairs 816 having layers with thicknesses withincertain ranges.

Preferred deposition thicknesses of some of the layers of apparatus 800will now be disclosed. It is generally preferred that a depositionthickness (t₁) of the magnetic layers 806 in each laminate pair 816 isgreater than a deposition thickness (t₂) of the nonmagnetic layers 808of the laminate pairs 816. For example, the deposition thickness t₂ ofthe nonmagnetic layer 808 in each laminate pair 816 may be about 10% orless of a total deposition thickness of the laminate pair 816.Accordingly the deposition thickness t₁ of the magnetic layer 806 ineach laminate pair 816 may be about 90% or more of a total depositionthickness of the laminate pair 816.

According to an illustrative range, the magnetic layer 806 in eachlaminate pair 816 may have a deposition thickness t₁ that is betweenabout 2 and about 100 nanometers, more preferably between about 20 andabout 75 nanometers, but may be higher or lower depending on the desiredembodiment. For example, the deposition thickness of magnetic layer 806described herein may vary to ensure that apparatus 800 has lowcoercivity (Hc) in both easy and hard axis directions. Furthermore, thedeposition thickness of magnetic layer 806 may vary to ensure a highmagnetic moment in apparatus 800. For example a high magnetic moment maycorrespond to greater than approximately 1 Tesla (T).

Furthermore, each of the magnetic layers 806 in each laminate pair 816may vary in deposition thickness, deposition material(s), fabricationprocess, etc., from one another in embodiments which include more thanone laminate pairs 816.

The nonmagnetic layer 808 in each laminate pair 816 may have adeposition thickness t₂ that is between about 1 and about 12 nanometers.According to preferred embodiments, the nonmagnetic layer 808 in eachlaminate pair 816 may have a deposition thickness t₂ that is less thanabout 8 nanometers. A nonmagnetic layer 808 thickness in each and/orsome laminate pairs 816 of less than about 8 nanometers was found toprovide better shielding than a comparable structure having a monolithicshield of the magnetic material.

However, according to some embodiments, one or more of the nonmagneticlayers 808 may have a deposition thickness t₂ greater than 12nanometers, e.g., to provide a strong structural integrity of apparatus800. Furthermore, the nonmagnetic layers 808 in the various laminatepairs 816 may vary in deposition thickness, deposition material(s),fabrication process, etc., from one another in embodiments which includemore than one laminate pairs 816.

In order to further improve magnetic shielding in apparatus 800, thelaminated portion 814 of the shields 820, 822 may, according to variousembodiments, account for as great a portion of the overall shields 820,822 as processing (e.g., liftoff, milling, etc.) and/or tape drivefunctionality constraints allow. Thus, according to some embodiments,the entirety of the one or more magnetic shields may be laminated. Inother words, one or both of the magnetic shields 820, 822 may notinclude a non-laminated magnetic portion 802 in some embodiments.According to other embodiments, the laminated portion 814 may accountfor a majority of the one or more magnetic shields 820, 822 whilenon-laminated magnetic portion 802 accounts for a minority of the one ormore shields. However, according to yet further embodiments, thethickness of the laminated portion 814 may account for about 10% or lessof the thickness of the overall magnetic shield 820. Accordingly, insuch embodiments the non-laminated magnetic portion 802 may account forabout 90% or more of the thickness of the overall magnetic shield 820.

According to preferred embodiments, the thickness t₃ of each of themagnetic shields 820, 822 in an intended media travel direction 824 maybe 2 to about 10 times a media wavelength of a frequency of a recordingcode compatible with the sensor structure 812, and in some approaches is2 to about 10 times a media wavelength of a lowermost frequency of arecording code compatible with the sensor structure 812. The mediawavelength of a lowermost frequency of a recording code may be describedas the average pattern repetition length that resides between portionsof data written to media, e.g., tape in the current embodiment. Forexample, according to various embodiments, the media wavelength may beabout 0.2 to about 2 microns, but could be higher or lower depending onthe embodiment.

Various embodiments preferably include multiple laminate pairs 816,e.g., to achieve a thickness t₃ of the magnetic shields 820, 822 asdescribed above. For example, in some embodiments, apparatus 800 mayinclude up to about 10 laminate pairs 816 on each side of the magneticsensor structure 812 (e.g., in each magnetic shield 820, 822). Itfollows that the configuration of the laminate pairs 816, e.g., numberof laminate pairs 816 on each side of the sensor structure 812, totalnumber of laminate pairs 816, thickness of each individual laminate pair816, etc., may vary depending on the embodiment. For example,embodiments associated with a low media wavelength may have magneticshields 820, 822 with a low thickness t₃ (e.g., still about 5 to about10 times the low media wavelength), thereby allowing the laminatedportion 814 to account for a greater amount of the overall magneticshields 820, 822.

As mentioned above, the magnetic shield(s) 820 and/or 822 of apparatus800 may include a non-laminated magnetic portion 802. As illustrated inFIG. 8, each of the non-laminated magnetic portion s 802 may sandwichthe laminate pairs 816 in the same shield therewith between thenon-laminated magnetic portion 802 and the sensor structure 812.Although apparatus 800 includes two non-laminated magnetic portion s802, e.g., a non-laminated magnetic portion 802 on each side of thesensor structure 812, sandwiching the laminate pairs 816 between therespective non-laminated magnetic portion 802 and the sensor structure812, in other embodiments, only a single non-laminated magnetic portion802 may be included on a single side of the sensor structure 812, e.g.,sandwiching the corresponding laminate pairs 816 on the single side ofthe sensor structure 812 between the non-laminated magnetic portion s802 and the sensor structure 812, etc. In other words, only one of themagnetic shields 820, 822 may include a non-laminated magnetic portion802.

Second magnetic shield 822 may have similar or the same structure and/orproperties as magnetic shield 820. For example, similar to magneticshield 820, the second magnetic shield 822 may have at least twolaminate pairs 816, where each pair 816 includes a magnetic layer 806and an electrically conductive nonmagnetic layer 808.

In other embodiments, the number of laminate pairs 816 in the firstmagnetic shield 820 may be different than the number of laminate pairs816 in the second magnetic shield 822.

However, according to other embodiments, the second magnetic shield 822may not have laminate pairs 816 of magnetic layers 806 and electricallyconductive nonmagnetic layers 808. For example, looking to FIG. 9A, inaddition to having a magnetic shield 820 with a laminated portion 814,an exemplary apparatus 900 is illustrated as having a second magneticshield 902 formed above the sensor structure 812 without laminate pairs816 of magnetic layers 806 and electrically conductive nonmagneticlayers 808. Rather, the entirety of the second magnetic shield 902 ismonolithic, e.g., a plated portion, a sputtered portion, etc. Accordingto some instances, embodiments having one of the magnetic shieldswithout laminate pairs 816 (e.g., such as the one illustrated in FIG.9A), may be implemented in a servo reader of a writer head or any othertype of magnetic head described and/or suggested herein.

Alternatively, looking to FIG. 9B, an apparatus 950 may include amagnetic shield 952 formed below the sensor structure 812 withoutlaminate pairs 816 of magnetic layers 806 and electrically conductivenonmagnetic layers 808. Rather, the entirety of the second magneticshield 902 may be a non-laminated magnetic portion while the magneticshield 822 above the sensor structure 812 includes a laminated portion814.

It should be noted that one or more of the magnetic shields 820, 822 mayhave a different structure than those described above, e.g., dependingon the desired embodiment. For example, in some embodiments, one or moreof the magnetic shields 820, 822 may include one or more laminated pairson both sides of a non-laminated magnetic portion, thereby sandwichingthe non-laminated magnetic portion along the deposition direction (e.g.,media travel direction 824).

As noted above, the number of laminate pairs 816 in the first magneticshield 820 may be different than the number of laminate pairs 816 in thesecond magnetic shield 822. For example, as shown in FIG. 10, the lowermagnetic shield 820 has more laminate pairs 816 than the upper magneticshield 822.

In further embodiments, a structure may have only a single magneticshield, which may be above or below the sensor structure. For example,as shown in FIG. 11, a structure 1100 may have only a lower magneticshield 820. A nonmagnetic conductor layer 1102 is positioned above thesensor 812, thereby providing an electrode for the sensor 812.Equivalently, a shield structure may be formed above the sensorstructure, where no shield structure is below the sensor structure.

In yet other embodiments, such as the embodiment 1200 shown in FIG. 12,a magnetic shield 820 and/or 822 may have a nonlaminated magneticportion 1202 sandwiched by one or more laminate pairs 816 positionedthereabove and therebelow. This embodiment makes the respective shieldsmore robust. When designing such shield structures, one should considerthe bending stiffness, which is proportional to the Young's modulus ofthe structure and the cube of the thickness of the film(s).

Embodiments described herein may advantageously protect the tape head oftape drive (e.g., see 100 of FIG. 1A) from, e.g., erosion, smearing,scratches, etc., which may cause electrical shorting events.Furthermore, the laminate pairs 816 may be implemented such that themagnetic shields (e.g., see 820, 822 of FIG. 8) have enhanced magneticpermeability and/or improved mechanical stability when compared tocommon highly magnetically permeable magnetic shield materials ofsimilar dimensions.

Moreover, referring now to the magnetic stability of embodimentsdescribed herein, e.g., the configuration of apparatus 800, because thelaminate pairs 816 are not continuously magnetic, magneto-striction mayremain desirably low, which may ensure magnetic stability of themagnetic shields 820, 822.

Accordingly, the structure and/or materials used to form the laminatepairs 816 may advantageously provide and/or serve as a portion of anabrasion-resistant magnetic shield while preserving the functionalconductivity of the corresponding tape head as well as the magneticfunctionality of the magnetic shields, e.g., as seen in apparatus 800.The improved tape head functionality achieved by the various embodimentsdescribed herein is advantageous, particularly in view of conventionalsmearing and/or scratching of the sensor structures, which has beenovercome by the present embodiments. Furthermore, the improved tape headfunctionality achieved by the various embodiments described herein maybe especially advantageous when implemented in tunnel valve structures,which may otherwise susceptible to shorting due to smearing ofconductive material across the tape head.

Preferred fabrication processes for the laminate pairs 816 and/orapparatus 800 may include, e.g., sputtering, ion beam deposition, atomiclayer deposition, etc. Furthermore, the laminate pairs 816 may befabricated by full film masking a stack of laminate pairs 816, and thenmilling and/or liftoff processing the resulting structure to the desiredwidth. Depositions, e.g., of the laminate pairs 816, of the magneticshields 820, 822, etc., may be performed sequentially in a multi-targetvacuum system, with or without magnetic field enhancement. Depositionsmay alternatively be performed in a continuous sputtering system, e.g.,for example where the sputtering occurs onto a wafer on a rotatingtable, etc.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: a magnetic sensorstructure; a magnetic shield having at least one laminate paircomprising a magnetic layer and an electrically conductive nonmagneticlayer; and a nonmagnetic spacer layer between the sensor structure andthe magnetic shield.
 2. An apparatus as recited in claim 1, wherein atleast some of the nonmagnetic layers comprise a material selected from agroup consisting of Ir, Ta, Ti and Ru.
 3. An apparatus as recited inclaim 1, wherein the magnetic shield has at least two of the laminatepairs.
 4. An apparatus as recited in claim 1, wherein the magneticshield further includes a non-laminated magnetic portion sandwiching thelaminate pairs between the non-laminated magnetic portion and the sensorstructure.
 5. An apparatus as recited in claim 1, wherein a thickness ofthe magnetic shield in a media travel direction is about 2 to 10 times amedia wavelength of a frequency of a recording code compatible with thesensor structure.
 6. An apparatus as recited in claim 1, wherein adeposition thickness of the nonmagnetic layer in each laminate pair isbetween about 1 and about 12 nanometers.
 7. An apparatus as recited inclaim 6, wherein a deposition thickness of the magnetic layer in eachlaminate pair is between about 5 and about 100 nanometers.
 8. Anapparatus as recited in claim 6, wherein a deposition thickness of thenonmagnetic layer in each laminate pair is about 10% or less of a totaldeposition thickness of the laminate pair.
 9. An apparatus as recited inclaim 1, wherein a deposition thickness of the nonmagnetic layer in eachlaminate pair is about 10% or less of a total deposition thickness ofthe laminate pair.
 10. An apparatus as recited in claim 1, wherein themagnetic shield is below the sensor structure, and further comprising asecond magnetic shield above the sensor structure and a secondnonmagnetic spacer between the sensor structure and the second magneticshield, the second magnetic shield having at least one laminate paircomprising a magnetic layer and an electrically conductive nonmagneticlayer.
 11. An apparatus as recited in claim 1, wherein the magneticshield is below the sensor structure, and further comprising a secondmagnetic shield above the sensor structure, the second magnetic shieldnot having laminate pairs of magnetic layers and electrically conductivenonmagnetic layers.
 12. An apparatus as recited in claim 1, wherein themagnetic shield is above the sensor structure, and further comprising asecond magnetic shield below the sensor structure, the second magneticshield not having laminate pairs of magnetic layer and electricallyconductive nonmagnetic layers.
 13. An apparatus as recited in claim 1,wherein the sensor structure includes a tunnel barrier layer.
 14. Anapparatus as recited in claim 1, wherein the magnetic shield has two toten laminate pairs.
 15. An apparatus as recited in claim 1, wherein themagnetic shield has at least one second laminate pair, and anonlaminated magnetic portion sandwiched between the at least onelaminate pair and the at least one second laminate pair.
 16. Anapparatus as recited in claim 1, further comprising: a drive mechanismfor passing a magnetic medium over the sensor structure; and acontroller electrically coupled to the sensor structure.
 17. Anapparatus, comprising: a magnetic tunnel junction sensor structure; anda magnetic shield having at least two laminate pairs, each paircomprising a magnetic layer and an electrically conductive nonmagneticlayer, wherein a deposition thickness of the nonmagnetic layer in eachlaminate pair is about 10% or less of a total deposition thickness ofthe laminate pair.
 18. An apparatus as recited in claim 17, wherein atleast some of the nonmagnetic layers comprise a material selected from agroup consisting of Ir, Ta, Ti and Ru.
 19. An apparatus as recited inclaim 17, comprising a nonmagnetic spacer layer between the sensorstructure and the magnetic shield.
 20. An apparatus as recited in claim17, wherein a thickness of the magnetic shield in a media traveldirection is about 2 to 10 times a media wavelength of a frequency of arecording code compatible with the sensor structure.